Based on our large and homogeneous photometric database of globular cluster observations taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope, a set of distance and reddening independent relative age indicators have been measured. The high quality of the color magnitude diagrams (CMDs) allows us to explore several variations of the classical age methods. The "vertical method" measures the magnitude difference between the main sequence turn-off (MSTO) and the horizontal branch (HB), the level of which is largely insensitive to age. The "horizontal method" measures the color difference between the MSTO and the red giant branch at a certain magnitude above the MSTO. The third method we will apply to our sample is similar to main sequence fitting. The observed CMDs are so well defined along the main sequence that we are able to superpose all the clusters in the same metallicity group and directly determine the differences in the color and magnitude of their turnoffs. This was practically impossible for previous databases because of the limited quality of the main sequence photometry. The observed "vertical", "horizontal" and main sequence fitting parameters will be analyzed in six metallicity subgroups and compared to the relations predicted by a library of isochrones constructed for this survey. Using the three independent methods and different theoretical models we will test the self-consistency of the results and the models at the same time.